IR 05000295/1988007

Safety Insp Repts 50-295/88-07 & 50-304/88-08 on 880302-04. No Violations or Deviations Noted.Major Areas Inspected: Containment Leak Rate Test (Cilrt) Procedure & Performance Witnessing & Review of Cilrt Results

ML20150D352
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	03/15/1988
From:	Maura F, Phillips M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20150D345	List: IR 05000295/1988007 ML20150D343
References
50-295-88-07, 50-295-88-7, 50-304-88-08, 50-304-88-8, NUDOCS 8803240061
Download: ML20150D352 (8)

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. . t U. S. NUCLEAR REGULATORY COMMISSION l REGION III  !

i i Reports No. 50-295/88007(DRS);-50-304/88008(ORS) I

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, Docket Nos. 50-295; 50-304 Licenses No. OPR-39; DPR-48 t i  !

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Licensee: Commonwealth Edison Company -

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P. O. Box 767

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Chicago, IL 60690 >

Facility Name: Zion Nuclear Power Station, Units 1 and 2 i

Inspection At: Zion, Illinois l

Inspected Conducted: March 2-4, 1988 i

Inspector:

Nhtm F. A. Maura

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) Approved By: Monte - l. . Phillips, Chief / N

Operational Programs Section Date !

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Inspection Summary Inspection on March 2-4,1988 (Reports No. 50-295/88007(DRS);  ;

No. 50-304/88008(OftS)T Areas Inspected: Routine, announced inspection by Region based inspector of j the containment leak rate test (CILRT) procedure; CILRT performance i witnessing; review of CILRT results; review of the Unit 2 CILRT report dated March 31, 1986; and review of licensee action on previous inspection  !

findings. NRC modules utilized during this inspection include 70307, 70313,  !

70323, 90713 and 9270 I

Results: No violations or deviations were identified, i

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i-r 8803240061 880318 PDR ADOCK 05000295 l Q DCD i

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DETAILS /

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l Persons Contacted i i Commonwealth Edison Company '

G. Armstrong, Shift Engineer

• Budowle, Assistant Superintendent,-Technical Services i J. Glover, Nuclear Services Technical ^

• Plim1, Plant Manager I

, *T. Printz, Assistant Technical Staff Supervisor (Test Director) l

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W. Reecher, Engineer, Technical Staf f (Test Supervisor)  !

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• T. Rieck, Superintendent, Administrative Services l J. Tiemann, Engineer Technical Staff (Test Supervisor)  ;

• T. Vandevoort GA Supervisor i Volumetric

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P. Zephier, J Service Technician i 1 i ERC j i P. Eng, Resident Inspector C. Mullins, Attorney, 0GC i

• Denotes persons attending the exit meet'.., of March 4, 198 .

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The inspector also contacted other licensee personnel including members i of the operations and technical staf ; Licensee Action on Previous Inspection Findings

(Closed) Open Item (295/85033-01; 304/85034-01)

Demonstrate that the isolation valve seal water system (IVSW) is capable of maintaining seal

water pressure at 1.1Pa, or above, if one of the penetration valves which l

the IVSW system is supposed to seal remains open. During July 1987 the licensee performed a test which simulated the failure of a penetration

! valve (RV0006 opened) in penetration P-60, containment pressure and

vacuum relief line. The IVSW pressure was recorded at the highest point in that IVSW supply line (penetration P-14). The inspector reviewed the test procedure and the strip chart recordings of the IVSW pressure at penetration P-14. The results showed that the IVSW pressure dropped from

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an initial pressure of 60 psig to a minimum of 56 psig when RV0006 velve

was opened. The minimum acceptable pressure is 52 psig (1.1 Pa). This

item is considered close ;

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3. ' Containment Integrated Leak Rate Test Procedure Review Procedure Review The inspector reviewed procedure No. TSS 15.6.10A, dated February 23, 1988, "Type A Containment Leak Rate Test,". relative to the requirements'of 10 CFR 50, Appendix J, ANSI N45,4-1972, and the Technical Specifications. ~ All inspector comments were satisfactorily resolve Clarifications of Appendix J Requirements To ensure the licensee's understanding of Appendix J requirements, the inspector conducted numerous discussions with licensee personnel during the course of the inspection. The following is a summary of the clarifications discussed with the licensee:

(1) The only methods of data reduction acceptable to the NRC are total time or point-to point as described in ANSI N45.4-1972, including a statistically calculated instrument error analysis. The following options are available to the licensee and are suggested in the following order:

(a) Total time (< 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> duration test) in accordance with Bechtel Corp. Topical' Report BN-TOP-1, Revision Whenever this method is used BN-TOP-1 must be followed in its entirety except for any section which conflicts with Appendix J requirement (b) Total time (> 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> duration test) using single I sided 95% UC (c) Proposed Regulatory Guide MS 021-5, Regulatory Position 13. If this method is utilized the licensee must submit an exemption request to NRC and receive approval i for its use prior to the expiration of the Type A test l frequercy requirements stated in the Technical l Specit1 cation I (2) Periodic Type A, 8, and C tests must include as-found results as well as as-left. If Type B and C tests are conducted prior to a Type A the as-found condition of the containment must be calculated by adding any improvements in leakage rates, which are the results of repairs and adjustments (RA), to the Type A test results using the "minimum pathway leakage" methodolog This method requires that:

(a) In the case where individual leak rates are assigned to two valves in series (both before and after the RA), the penetration through leakage would simply be the smaller of the valves' leak rate __ _ . .

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(b)' In the case where a leak rate is obtained by pressurizing between two isolation valves and the individual valve's leak rate is not quantified, the as-found and as-left penetration through-leakage for each valve would be 50% of the measured leak rate if both valves are repaire '

! (c) In.the case where a leak rate is obtained by pressurizing between two isolation valves and only one valve is repaired, the as-found penetration leak rate would conservatively be the final me nured leak rate, and the ,

as-left penetration througt leak rate would be zero (this l assumes the repaired valve eeks zero).

(3) Penetrations which are required to be Type C tested, as l described in the FSAR and SER, must be vented inside and '

outside the containment during the CILRT. All vented penetrations must be drained of water inside the containment  !

and between the penetration valves to assure exposure of the containment isolation valves to containment air test pressur The degree of draining of vented penetrations outside of containment is controlled by the requirement that the valves b l subjected to the post-accident differential pressure, or proof that the system was built to stringent quality assurance standards comparable to those required for a seismic syste (4) Whenever penetration configurations during a CILRT deviate from the ideal, the results of LLRTs for such penetrations must be added as a penalty to the CILRT results at the 95% confidence i level. Thi: penetration leakage penalty is determined using l the "minimum pathway leakage" methodology. This methodology is i defined as the minimum leakage value that can be quantified  !

through a penetration leakage path (e.g., the smallest leakage l through two valves in series). This assumes no single active-failure of redundant leakage barriers. Additionally, any increase in containment sump, fuel pool, reactor water, or i suppression pool level during the course of the CILRT must be taken as a penalty to the CILRT result If penalties exist, they must be added (subtraction is never permitted) to the upper confidence level of the CILRT result (5) The start of a CILRT must be noted in the test log at the time the licensee determines that the containment stabilization has been satisfactorily completed. Reinitializing a test in progress must be "forward looking," that is, the new start time must be the time at which the decision to restart is mad '

This also implies that the licensee has determined that the test has failed, and has enough data to quantify the leakage rate. Any deviation from these positions should be discussed, and documented, with the NRC inspector as they occur to avoid later invalidations of the test results. Examples of 4 acceptable deviations of reinitializing the start time of the test in the past are: time at which a leaking penetration

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which has an. obvious effect on the' test data was secured,

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acciden'tal opening and later closing of a valve which has an obvious effect on the test date, and the time at which an airlock outer door was closed and the inner door.was ope (6) The supplemental or verification test should start within one hour after the completion of the CILRT. If problems are encountered in the start of the supplemental test, data recording must continue and be considered-part of the CILRT until the problems are corrected and the supplemental test can begi (7) For the supplemental test, the' size of the superimposed leak rate must be between 0.75 and 1.25 times the maximum allowable leak rate La. The. higher the value, the bette The supplemental test must be of sufficient duration to demonstrate the accuracy of the tes The NRC looks for the results to stabilize within the acceptance criteria, rather than the results being within the acceptance criteria. Whenever the BN-TOP-1 tathodology is being used, the length of the

- supplement al test cannot be less than approximately one-half the length of the CILR (8) During a CILRT, it may become necessary to reject or delete specific sensors or data points due to drifting or erroneous sensors, or data outlier Data rejection criteria should be developed and used so that there is a consistent, technical:

basis for data rejectio One example of an acceptable method for data outliers is considered in an Appendix to ,

ANSI /ANS 56.8-198 Sensor data rejection criteria should be plant specific and based _upon a sensor's trend relative to the average scatter, sicpe and/or absolute output-of the senso (9) The water level in the steam generators during the CILRT must f be low enough to ensure it does not enter the main steam lines '

unless flooding of the main steam lines is called for.in the loss of coolant emergency procedure, q

(10) An acceptable method for determining if the sum of Type B and C

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tests exceeds the 0.60 La Appendix J limit is to utilize the

"maximum pathway leakage" method. This methodology'is defined as the maximum leakage value that can be quantified through a-penetration leakage path (e.g. , the larger, not total, leakage 1 of two valves in series). This assumes a single active failure I to the better of two leakage barriers in series when performing Type B and C test (11) Test connections must be administratively controlled to ensure i their leak tightness or otherwise be subject to-Type C testin One way to ensure their leak tightness is to cap,

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with a good seal, the test connection-after its us Proper

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administrative controls should ensure valve closure and cap {

reinstallation within the local leak rate testing procedure, '

and with a checklist prior to unit restar (12) Whenever a valve is replaced, repaired, or repacked during an outage for.which Type A, B, and/or C surveillance testing was scheduled, local leak rate testing for the as-found as well as the as-left condition must be performed on that penetratio In the case of a replaced valve, the as-found test can be waived if no other containment isolation' valve of similar design exists at the sit (13) The periodic retest schedule for each penetration subject to Type B or Type C testing, except for airlocks and penetration-employing a continuous leakage monitoring system, shall be every refueling outage, but in no case shall the interval be greater than two year . Containment Integrated Leak Rate Test Witnessing The inspector reviewed the calibration data and determined all the instruments used in the CILRT had been properly calibrated and that the correct weighting factors had been placed in the computer program as required. The following instrumentation was used throughout the test:

Type Quantity RTDs 29 Humidity 10 Pressure gauges 2 Flowmeter 1 Witness of Test The inspector witnessed portions of the CILRT on March 2-4, 1988, and noted that test prerequisites were met and that the appropriate revision to the surveillance procedure was followed by test personne Valve lineup for the following systems were verified correct to insure that no fluid could enter the containment atmosphere and that proper venting and draining was provided:

(1) Containment purge and relief (2) Heating steam (3) Instrument air (4) Isolation valve seal water (5) Main steam (6) Nitrogen (7) Service air

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< . , Test Results Evaluation CILRT Data Evaluation A 13.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> short duration, CILRT was performed during March 2-3, 1988, at approximately 64.5 psia following satisfactory completion of the required temperature stabilization perio Data was collected every 15 minutes. The inspector independently monitored and evaluated leak rate data using total time (Bechtel Topical Report BN-TOP-1, Revision 1) formulas to verify.the licensee's calculations of the leak rate and instrument performance. There was excellent agreement between the inspector's and licensee's results as indicated by the following summary (units are in weight percent perday):

Measurement Licensee Inspector Leak rate measured during CILRT (Lam) 0.027 0.027 Lam at upper 95%

confidence level 0.068 0.068 Appendix J acceptance criteria at 95% UCL: < 0.75La = < 0.075 weight percent per da No correction for significant changes in sump and pressurizer vessel water levels were required. Since no deviations from the required valve lineups occurred, and no repairs were performed on a penetration prior to the ILRT, the calculated leakage rate at the 95% UCL constitutes the as-found, as well as the as-lef t, condition of the containment. During pressurization the personnel airlock inner door shaft seals developed a leak. The licensee closed the outer door and opened the containment to airlock equalizing valve for t'.e duration of the test, Supplemental Test Data Evaluation After the satisfactory completion of the CILRT a known leakage rate (based on inspector's independent readings and calculatiuns) l of 8.07 scf, equivalent to 0.102 weight percent per day at accident pressure, was induced. Data was collected and analyzed by the j licensee every 15 minutes. The inspector independently monitored ;

and evaluated leak rate data to verify the licensee's result !

After 6.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> the supplemental test was terminated with excellent i results as indicated by the following summary (units are in weight percent per day):

Measurement Licensee Inspector Measured leakage rate, Lc, during supplemental test 0.119 0.119

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Measurement Licensee laspector Induced leakage rate, lo 0.100 0.102 Lc-(Lo+ Lam) -0.008 -0.010 Appendix J acceptance criteria: -0.025 5 [Lc-(Lo+ Lam)] 5 + 0.025 l No violations or deviations were identifie l l Review of Zion Unit 2 Reactor Containment Building Integrated Leak Rate Report The inspector reviewed the licensee's "1985 Integrated Leak Rate Test of Zion Unit 2 Reactor Containment Building" report submitted to the NRC on March 31, 1986 and determined that it accurately reports the leak rates and events regarding the Unit 2 Type A test performed in September 198 . Exit Interview

The inspector met with licensee representatives (denoted in Paragraph 1) I on March 4, 1988 at the conclusion of the inspection. The inspector summarized the scope and findings of the inspection. The licensee acknowledged the information and did not indicate that any of the information disclosed during the inspection could be considered I proprietary in natur !

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